Patched lumber



@si. 15, 1934. Q M 5055 ET AL 1,976,722

PATCHED LUMBER Filed April 21, 1953 lifi/ 66055 INVENTOR W P. @055 Patented Oct. 16, I934 UNI-TED STATES PATCHED LUMBER Oliver P. M. Goss and Worth 0. Goss, Seattle,

Wash, assignors to Carlisle Lumber Company, Onalaska, Wash, a corporation of Washington Application April 21, 1933, Serial No. 667,219

6 Claims.

This invention relates to the manufacture of lumber and more particularly to a method of producing lumber of high classification from material which by reason of defects therein, such as knots, pitch pockets, stains, scars, or other imperfections, would normally be placed in an inferior grade.

Explanatory to the present invention, it will be stated here that in the manufacture of lum- 10 her, as now generally carried on, whether it be common lumber for rough work and framing or lumber of the finer grades, such as for finishing, there is a very material percentage that is classified in the lower grades by reason of its containing some defect, such as a. knot, or pitch pocket. It has been the usual practice to cut out that part of the board containing the defect, but in a majority of cases this results in a. waste of material and a decrease in value by reason of the production of short pieces not classifiable with the higher grades, particularly in which length is a factor.

Heretofore, defects have been removed from lumber and patches applied to fill the openings resulting from the removal of the defective parts, but to our knowledge, the application of the patches, or plugs, was done only with the object of filling the recess and not primarily to strengthen the piece or to increase its value. A common method of patching has been to bore out the defeet, then to thread the bore and to apply a threaded plug, as disclosed in U. S. patent to H. E. Leash. This method does not afford means of obtaining the maximum strength in the patched piece, nor does it insure a desired tight- ,ness between the plug and piece after the lumber has been placed in use or exposed to weather.

In view of the above, it has been the principal object of the present invention to provide a. practical and economical method and means whereby knots, pitch pockets, scars and other defects, may be removed from lumber that is otherwise of high grade, and prepared patches applied thereto in a manner whereby the patches are not easily detected; whereby the strength and usefulness of the piece repaired is not impaired, and the strength and appearance so improved that it is of higher classification and of greater value by reason of the elimination and repair of the defect without change in length of the piece.

More specifically stated, the present invention resides in the novel method of removing a defective portion from a lumber piece and in the provision and application of a repair patch of a specific form to the piece so that the strength of the piece is in no way impaired and the patch tightly and permanently retained in place.

It is also an object of the invention to provide a form of glued in patch that may be pressed into place and which does not require the use of ztzlamps to hold it while the glued joint is set- Another object resides in the preparatory treatment of the piece and patch whereby the tightness and integrity of the joint between these parts after they are assembled is insured.

Other objects reside in the matching of grain of the patch with that of the piece to which it is applied so that the application of patches will not be noticeable or in any way detract from the appearance of the piece repaired.

It is also an object to provide a method of patching that is commercially economical.

In accomplishing these and other objects of the invention, we have provided the improved details of construction, the preferred forms of which are illustrated in the accompanying drawing, wherein- Fig. 1 is a perspective view of a lumber piece to which a. patch has been applied, and showing also a pocket or recess in the piece and a patch to be applied thereto.

Fig. 2 is .a plan view of a pocket as prepared in a piece of lumber in removal of a defect, for reception of a patch in accordance with the present invention.

Fig. 3 is a section through a patched piece of lumber in a plane lengthwise of the patch.

Fig. 4 is a cross section taken on line 44 in Fig. 3.

Fig. 5 is a perspective view of a patch.

Fig. 6 is a view illustrating one type of machine suitable for cutting out the defect and for forming the pockets in a piece to be repaired.

Fig. 7 is a view diagrammatically illustrating a mechanism for preparing the patches.

Referring more in detail to the drawing- In Fig. 1, 1 designates what may be a piece of ordinary lumber and 2 designates a patch that has been applied thereto, in accordance with the present invention; 3 designates a pocket that has been prepared at another place in the board for reception of a patch 2a disposed above it.

In the manufacture of this lumber, the boards are taken while in the rough, as they come from the drying kiln, and by use of revolving cutters or other suitable means, defects such as knots, pitch pockets, scars and the like, are removed from the piece leaving at each place a pocket 3, for reception of a patch; it being the intention that cutters of various size be provided for use in removal of defective portions of different areas. I

A preferred form of machine for cutting out the defects, and at the same time preparing a pocket for the patch, is illustrated in Fig. 6, and it consists of two cutter heads 6-6 arranged in alinement on parallel driving shafts 7-7, rotating in synchronism and in opposite directions so that each will cut with the grain of the piece. Each head is equipped with two or more cutters 8 arranged to cut V-shaped grooves of a selected depth and the cutters on each head are so spaced that the grooves made thereby will overlap, thus forming the end surface of the pocket in a series of symmetrical V-shaped ridges 9 and grooves 10. By reason of the circular path of the cutters, and by reasonof definitely limiting the extent to which they are adjusted into the piece in cutting the pocket, the end surfaces of the latter will be symmetrically tapered from one side of the piece to the other so that the patch, which is cut to conform to the shape of the pocket, will have a wedging effect when it is applied thereto and pressed into place.

It will be observed by reference to Fig. 5, that the patch is provided at its ends with V-shaped ridges 12 arranged to register within the V- shaped grooves of the pocket when it is applied thereto, and it is apparent that by pressing the patch into place, it may be caused to fit snugly into place with all its end and side surfaces tightly fitted to corresponding surfaces of the pocket. Patches of this character are made by suitable milling machines and are made in various sizes to fit the various sizes of pockets that are to be provided therefor. They may be in various lengths and widths and comprise one or a plurality of pointed end portions, and these points may be made as long as practical to secure the maximum area for the glue joint.

It is the intention that the material for the patches be obtained by cutting out the clear parts of low grade lumber and that care shall be taken to match as nearly as practical the grain and color of the patch with the grain and color of the piece to which it is applied. Also, the finished patches should be slightly oversize so that when applied to the pockets they will have a snug fit. Also, it is intended that when applied they shall extend just slightly beyond the opposite surfaces of the piece before it is surfaced.

In carrying out the method, the lumber to be patched is first passed through the drying kiln and its moisture content reduced to approximately twelve per cent. The prepared patches, likewise, are kiln dried to reduce their moisture content to approximately nine per cent. This is to insure a continued tightness of the patch after it has been applied since any shrinkage that might occur therein will be less than that of the piece by reason of the difference in moisture content at the time of application.

It is also desirable that the patches be passed through a warming oven just prior to their application, as a means of slightly overdrying and shrinking the end portions to compensate for any expansion that may take place incident to application of glue to these parts.

In some instances, or for some special classes of lumber, it may be desirable to add to the security of the patch by the insertion of one or more dowel pins through the parts, such a pin being shown at 14 in Fig. 3. It is to be understood, however, that in most instances these pins will not be required.

In Fig. 7 we have illustrated a suitable form of machine for making patches; it being remembered that these should be made so as to snugly fit the pockets provided by the cutter heads. This machine comprises a revolving cutter head 15 with cutters 16, similar to those in the heads 6. Adjacent the head is a support 17 mounted to swing on a pivot shaft 18 which is axially parallel with the axis of the cutter .head and is spaced from the cutters a distance corresponding to the radius of the ends of the pockets 3. The piece of material selected to form the patch is placed on the support 17 andis held by a suitable clamp as at 20. Then the base is rotated by any suitable means about the pivot 18 to bring the end of the patch piece against the cutter which operates to round ofi the end of the patch to exactly fit the end of the pocket to which it is to be applied. Then the patch piece is reversed in position on the base and its opposite end is rounded off in a like manner. By accurately positioning the piece on the support when it is reversed, it may be cut to the exact length required.

In placing the patch piece on the support it is so arranged that the grain of the piece is lengthwise of the finished patch so as to match with that of the lumber to which it is'to be applied.

It will here be mentioned also that since the cutters 8 of the pocket forming cutter heads, and also those of the head 15, are formed with a series of V-shaped symmetrically formed teeth of equal size, and since the path of travel is in a circular path, they will form grooves whereby a wedging effect is provided when the patches are applied. For instance, the wedging fit of the ridges 12 at the ends of the patch within the grooves 9 of the pocket is shown in the sectional view of Fig. 4, and in Fig. 2 the wedging fit of the patch in the pocket is shown.

It is apparent also that the length of the grooves of the pocket and the cooperating ridges .of the patch should be as long as practical and that they should be as close as possible in order to insure the maximum area and strength for a glued'joint.

In applying the patches, a suitable transparent glue is applied to their side and end surfaces. Also, the glue is applied to the sides and ends of the pocket. Then the patch is pressed into place. After the patches have thus been applied, and the joint has sumciently set, the lumber is passed to the planer and is surfaced, thus leaving the surfaces of the piece and patch in the finished piece fiush with each other.

Patches so applied remain rightly and securely in place and cannot be pushed out. Tests have proved that the patch secured by the joint as above described increases the strength of the piece to that of a piece without defects. This is mainly by reason of the fact that in the provision of the end surfaces of serrated form, the area of surface provided for the glue joint is so increased that the strength in the joint is equal to the cross section of the piece.

By patching lumber in this way, low grade of the grain of the piece; said slot having parallel side walls and its opposite end surface symmetrically inclined inwardly and formed with a plurality of contiguous V-shaped grooves and ridges, and a patch of like material fitted and glued within the slot and having its grain alined with the direction of the grain of the piece and formed at its ends with contiguous V-shaped ridges and grooves applicable to those of either end of the slot in a downwardly wedging joint, and a dowel pin extended through the patch and piece.

2. A piece of commercial lumber having an essentially rectangular defect removing slot cut therethrough and formed with serrated end surfaces and a patch piece applied to and glued within the slot and having its ends serrated and fitted to the serrated end surfaces of the slot in a close joint.

3. A piece of commercial lumber having an essentially rectangular defect removing slot cut therethrough and extending in the direction of the grain of the piece and formed at its ends with a plurality of deep \l-shaped grooves extending from one surface of the piece to the other and a patch piece of like material with grain lengthwise thereof, fitted to and glued at its ends within the slot and having its end surfaces formed with V- shaped tongues which fit tightly within the grooves at the ends of the slot.

4. A piece of commercial lumber having an essentially rectangular elongated defect removing slot cut therethrough and extending in the direction of the grain of the piece; said slot having at each end a plurality of deep v-shaped grooves contiguous to each other and extending in the direction of the slot through the piece, and a patch piece of like material fitted in the slot and having V-shaped tongues at its ends wedged within and secured by glued joints in the V-shaped grooves.

5. A piece of commercial lumber formed with an essentially rectangular defect removing slot cut therethrough lengthwise of the grain of the piece; said slot having parallel side walls and its opposite end surface curved inwardly toward each other and formed with a plurality of contiguous V-shaped grooves extending along the end surfaces in planes parallel with the side walls of the slot, and a patch of like material fitted in the slot and having its grain alined with the direction of the grain of the piece and formed at its ends with contiguous V-shaped tongues curved to conform to and wedged and glued within the end grooves of the slot.

6. A piece of commercial lumber formed with an essentially rectangular defect removing slot cut therethrough from top to bottom surface and lengthwise of the grain thereof and formed with parallel side walls and at its ends with contiguous and alternating V-shaped grooves extending in planes parallel with the side walls of the piece and arcuately curved inwardly from top to bottom surface of the piece about a common axial line, and a patch piece of like material, with the grain extending lengthwise thereof, applied tightly within the slot and glued at its ends and sides therein; said patch piece having its opposite ends formed with alternating V-shaped grooves and ridges arcuately curved about a common axial line and corresponding in curvature to the curvature of the end grooves and ridges of the slot and interfitting therewith in downwardly and laterally wedging joints.

OLIVER P. M. GOSS. WORTH C. GOSS. 

